For joists that are SYP or Douglas Fir, in good condition, 10 inches tall, 1.5 inches wide, 16 inches on center, and 10 feet long between supports, the deflection calculated is 0.118 inches.
This translates to a deflection of L / 1020.
Since the maximum deflection for tile is L / 360, and for natural stone is L / 720, your floor is rated for Ceramic tile or Natural stone, Congratulations.."inadequate structure" is no more.now for the "schluter" under the tub that was in hopes of never getting water under tub to sub-floor just in cass anything went bad(this is going to be my boy's masterbath)right now he is 4 never know what kid's can do